Effect of a bone marrow stimulator of antibody producers on virus-specific antibody formation in animals infected with flaviviruses

The injection of the marrow stimulator of antibody-producing cells (SAPC) into animals infected with Japanese encephalitis and tick-borne encephalitis viruses stimulated the formation of virus-specific antibodies in the infected animals, increasing antibody production 8- to 16-fold. Such SAPC-induced stimulation of the formation of virus-specific antibodies is observed in cases of both acute and chronic virus infection. The prospects of using the preparation of SAPC are discussed.     

Multiplicity of affinity modification of RNAse during its alkylation with a reactive analog of 5-deoxyribonucleotide

The interaction of pancreatic RNase with 5'-deoxyribodinucleotide alkylating derivative, 4-(N-2-chloroethyl-N-methylamino)benzylamide of d(pTpA) d[(ClRCH2NH)pTpA], was studied. The unreactive oxyanalogue d[(HORCH2NH)pTpA] was shown to act as competitive inhibitor of cCMP hydrolysis by RNase. d[(ClRCH2NH)pTpA] irreversibly inactivated RNase. A protective effect was exerted by d(pTpA) and d[(HORCH2NH)pTpA]. The modification, although having an affinity character, was not accompanied by total inactivation of the enzyme. It was supposed that covalent bonding between the reagent and enzyme induced the dinucleotide displacement from the recognition site. The formation of four RNase monolabeled forms retaining the activity in the hydrolysis of cCMP and poly(U) was demonstrated.     

Protection from foot-and-mouth disease virus in naturally-susceptible animals by a linear polymer of a synthetic peptide]

Linear polymer of a peptide corresponding to the fragment 142-155 of the foot-and-mouth disease virus A22(550) protein (VP1) was synthesized. Whereas the monomeric peptide was only slightly immunogenic, the polymer induced virus-neutralizing antibodies in rabbits and protected 100% guinea pigs. Sheep vaccinated once and cattle vaccinated twice were stable against infection with the homologous virulent foot-and-mouth disease virus.     

Effect of Cation Concentration on Molecular Dynamics Simulations of UDP-Glucose

Abstract

Glycosyl esters of nucleoside di or mono-phosphates, generally referred to as “sugar nucleotides”, serve as a sugar donors during the biosynthesis of oligo- and polysaccharides; they are therefore of a primary importance in carbohydrate metabolism in the living world. Molecular dynamics simulations were used to explore the conformational flexibility of one nucleotide sugar, UDP-glucose (UDP-Glc). The AMBER program package was used with some new parameters especially developed for nucleotide sugars. Several simulations on this molecule in aqueous solution, each of 2 ns duration, were carried out for increasing concentrations of monovalent K⁺ and divalent Mg²⁺ ions. For the monovalent ion, it is revealed that its presence and concentration is crucial for the conformational behavior, resulting in the stabilization of the extended conformation. The preferred location of K⁺ is in close proximity to the negatively charged phosphate oxygens, but the ion moves freely and can occupy other sites. Since the size of this cation is close that of the water molecules, the hydration scheme is not perturbed. Completely different results are obtained when the divalent Mg²⁺ cation is introduced in the simulation. A very strong interaction is established between the phosphate group and the cation; as a result the UDP-Glc molecule is locked in a rigid extended geometry. The analyses of the trajectories provide new insight on the role of the metal ion in the catalytic mechanism of glycosyltransferases.     

The proto-Nucleic Acid Builder: a software tool for constructing nucleic acid analogs

The helical structures of DNA and RNA were originally revealed by experimental data. Likewise, the development of programs for modeling these natural polymers was guided by known structures. These nucleic acid polymers represent only two members of a potentially vast class of polymers with similar structural features, but that differ from DNA and RNA in the backbone or nucleobases. Xeno nucleic acids (XNAs) incorporate alternative backbones that affect the conformational, chemical, and thermodynamic properties of XNAs. Given the vast chemical space of possible XNAs, computational modeling of alternative nucleic acids can accelerate the search for plausible nucleic acid analogs and guide their rational design. Additionally, a tool for the modeling of nucleic acids could help reveal what nucleic acid polymers may have existed before RNA in the early evolution of life. To aid the development of novel XNA polymers and the search for possible pre-RNA candidates, this article presents the proto-Nucleic Acid Builder (https://github.com/GT-NucleicAcids/pnab), an open-source program for modeling nucleic acid analogs with alternative backbones and nucleobases. The torsion-driven conformation search procedure implemented here predicts structures with good accuracy compared to experimental structures, and correctly demonstrates the correlation between the helical structure and the backbone conformation in DNA and RNA.     

Ultrastructural characteristics of the capillary basement membrane of the cerebral cortex in normal state and in severe focal diseases]

The capillary basal membranes of the cerebral cortex in adult rats and man have similarultrastructure in normality. The same formation of capillaries of the cerebral cortex of 1 day old rats is characterized by a not uniform structure and relatively low electron-optical density. The capillary basal membrane of the cortex of patients not older than 30 with severe focal lesions of the brain has increased thickness in some portions where it iscomposed of a homogenous substance, osmophilic granules, light cavities of different size and shape, vesicles restricted with a sheath and rare dense bodies. In elderly patients older that 40 the capillary basal membrane in thicker zones appears to be more electron dense and homogeneous than in younger patients.